Method and machine for testing textiles



Sept. 23, 1930. E scH ET AL V 1,776,514

METHOD-AND MACHINE FOR TESTING TEXTILES Filed 001;. 3. 1928 Fig. 5.

INVENTORS 40800 Patented Sept. 23, 1930 UNITED STATES PATENT OFFICE JOHN PAUL LAETSCH, OF ZURICH, SWITZERLAND, AND PAUL LITTY, OF LEIPZIG,

' GERMANY METHOD AND MACHINE FOR TESTING TEXTILES Application filed October 3, 1928, Serial No. 309,938, and'in- Germany October 7, 1927.

This invention relates to the testing of textile material and more particularl to testing i cial silk, cotton and like fibrous material as produced by preparatory textile machinery is too weak to withstand the pull imposed upon it by the fliers or creels of these machines. Accordingly, in order to hold the fibres together, it is customary to-impose a twist in this roving. The twist gives the several fibres the necessary resistance against gliding and sufiicient breaking strength to the roving in general. T'wo considerations govern the amount of twist imposed in the roving: it must not be twisted so little that it is not evenly stretched in the succeeding processes, but it also must not be twisted too hard because then too much resistance is offered in the following drawing processes.

It has been determined in practice that the degree of the twist to be imposed is closely related to the length of the fibre, and experience has shown that a roving consisting of short fibres must have more twist than a roving of the same size, or weight, consisting of longfibres. Even so only the most skilled practical spinners are capable of determining with approximate accuracy the degree of twist to be imposed because many factors must beconsidered. For example the degree of twist changes with the size of the roving and, for the same length of fibre, increases as the size decreases; the humidity of the room where the material is being worked is influential, also the humidity of the material itself because there is less resistance to gliding between the fibres when dry and more twist is required to balance this conditigr the amount of tension (as of spinning) under which the roving is produced must be considered because roving produced with slack tension will have less glide resistance than roving having the same twist but produced hand with a higher tension. This also applies to yarn.

Until the testing machine of this invention was produced the usual test of roving for proper twist was merely by watching the way it was running in the machines, or by according to the experience of the operatlve. Those skilled in the art have long recognized theinadequacy of such tests, especially in view of the fact that they are made only with short pieces of materiah Because the twist is imposed in the roving in order to increase the glide resistance of the fibres and thus to bring the breaking strength i to a predetermined value, it is obvious that this definite breaking strength can be used as a measure for determining the degree of twist to be given to the roving. This fact is the basis of the mechanical method of testing the strength of the roving or yarn and of the machine by which this method-may be practiced.

W'hen roving is placed under a gradually increasing tension a time comes when the natural limit of elasticity of the material is 7 reached whereupon the fibres begin to glide or'slide by each other, This gliding of the fibres continues for a brief period before the tension i mposedactually breaks the roving.

Thus there is a stretching before breaking and just beforebreaking the resistance is loweredconsiderably. The amount of resistance which a roving has under increasing pull just before the fibres glide apart will be called draft resistance, although generally speaking draft resistance, glide resistance and breaking strength are all one and the same. Bearing the foregoing in mind the principle of the new method may be stated ,that a strand of a certain size, 01' weight s5 should have a predetermined draft resistance which is given through more or less twist.

While the draft resistance is dependent upon the size of the strand it also is dependent upon the length of the section, between two fixed points, that is being tested. The

draft resistance is greatest when the distance between the two points is-equal to the length of the staple, or fibre, of the material; decreases slowly as the length of the section is increased; and becomes constant when the distance between the two points is fromtwo to three times that of the longest fibre. Thus the length of fibre in the strand may be disregarded if the test is made upon a long enough section of the material. This greatly,

. given and shown in the accompanying drawing, in which Figure l is a diagrammatic View, in elevation, of one form of such mechanism; Fig. 2 is a diagrammatic View, in elevation, of another form thereof; and Fig. 3 is a view showing the grooved disk, of Fig. 1, in section.

Referring first to Fig. l the strand material S, such as roving or yarn, wound on a spindle 4 by a preparatory textile machine, is led through two pairs of rollers 5, .5 and 6, 6 which are simultaneously driven in such a way that the pair 6, farthest from the spindle, deliver slightly faster than the pair 5. As illustrated the rollers of each pair are driven by gearing 9 and 10, this gearing being such that the surface speed of the rollers '6 is greater than that of the rollers 5. The

gearing is driven by a shaft 11 which may be r rotated by a hand crank 12 or by power.

Astand 16 carricsa'sraiile 17 of quadrant shape graduated to indicate the variable position of a pointer 18 pivotally mounted at 19 on the stand 16. An adjustable weight 20 on the pointer maintains it normally at the zero (lower) end of the scale. Integral with the pointer is a scale arm 21 having a hookshaped end 22. The arrangement is such that when the pointer hangs vertically the scale arm stands above the horizontal.

The stand 16 carries a disk 25 rotatably mounted on a shaft co-axial with the pivot 19. The disk 25 is positively and continuously driven in the direction of the arfow, slowly, as by gearing 26 on a counter-slnift 27 that may be driven from the shaft 11? as by bevel gears 28. The disk 25 has a V-shaped, circumferential gro gve. A weighted 1 30, loosely piv oted on"thes'ca'le arm. has a complementally shaped gripping end lying within the groove that will grip the disk only when the scale arm moves upward.

Referring now to Fig. 2 the design there illustrated is the same as shown in Fig. 1 with respect to the spindle, feed rollers, and

scale with its weighted pointer and hooked scale arm.

two pairs of feed rollers and the intermediate loop L is elongated and reeved over the hook on the scale arm. The faster delivery by the rollers 6, 6 causes the scale arm to be pulled down, and the weighted pointer moved up across the scale, until the limit of draft resistance is reached. The disk 25, or the screw 38, rotates freely past the gripping pawl during all downward'movement of the scale arm. When the limit of draft resistance is reached the fibres of the strand begin to glideby each other permitting the scale arm to rise under the influence of the weighted pointer. The strand would be broken if this upward movement were permitted to continue without control. The pawl 30, or pawl 37, act immediately to stop the accelerated upward movement of the scale arm by being brought under the control of the disk 25, or

screw 38, thus causing the scale arm to lift only slowly at the rate permitted by the speed of rotation of the disk or screw. The strand is thus at once released of its tension. because the scale arm is relieved from the influence of the weighted pointer, and the speed of return of the pointer tozero position is entirely under control of the slowly rotating disk or screw. This continues, with the st rand able to run freely without breaking, until the thin or weak portion has passed the delivery rollers (l, (S. Then, if a stronger portion of the strand comes into play the increased strength will again draw the scale arm down and the control of the tension will be transferred back to the weighted pointer by reason of the fact that the downward movement of the scale arm automatically releases the pawl. Thus the strand can run uninterruptedly. for as long a time as may be desired for testing, without ever being broken. It will be observed that the influence of the weight decreases as it nears the zero osition, hence a somewhat weaker portion 0 the strand may act to release the pawl as well as a portion of V H normal stren fli irf It is wellknown that it is very desirable to have all roving of an egen weight or size if measured at short length and an even amount of twist in a certain stated length. According to the method'herein described not only are the slightest variations in thickness and twist shown as a variation in the draft resistance, but also errors in the proper setting of the preparatory machinery are shown, especially those which go over a great length of roving. All these show very clearly in the changeable draft resistance.

It will be recognized that the determination of the necessary twist for every weight or size of roving and like strand material, as taught by this invention, is a considerable step forward in the art of spinning.

The nature and scope of the invention having been indicated and the principle of the method having been explained, together with a description of a simple mechanism for practical use of the method, whatis claimed as new, is

1. The method of testing the strength of fibrous strand material which comprises placing a definite tension on a section of a continuously advancing strand, said section being considerably longer-than the length of the staple or fibre, relieving the tension for each weak portion encountered and simultaneously causing the fibres to glide at a fixed rate of speed, and restoring the original tension when the advance of the strand presents a succeeding portion of the requisite strength, thus causing the strand to advance without breaking throughout the entire period of the test. i

2. A machine for testing the draft resistance in continuously running fibrous strand material comprising feeding-in and delivery rollers for the strand, roller driving mechanism for causing delivery of the strand at a faster rate, a scale arm over which is looped a section of the running strand extending from the feeding-inv to the delivery rollers, a weighted pointer connected to said scale arm that traverses a scale and is movable away from zero position by the tension applied by thestrand to'said scale arm, and

means for causing the pointer to move toward zero position at a fixed rate of speed whenever the draft resistance within said section of the running strand is less than the draft resistance as indicated on the scale by said weighted pointer.

3. A machinefor testing the draft resistance of roving, and the like, comprising means for continuously advancing the roving, means for applying a predetermined tension to the running roving, means for indicating variations from-the normal draft resistance throughout a section of the running roving that is gripped at each end, and supplementary means acting automatically to'relieve the tension when the indication shows a weak portion in said section.

4. Apparatus to work themethod'accordconstant rate of speed, and then ing to claim 1 in which the fibrous strand passes through pairs of rollers one pair of of which has a predetermined faster delivery than the other and between which a loop of the strand is guided over an arm, a scale, aweighted pointer connected to the arm and movable across said scale to indicate the amount of the draft resistance in the passing loop, a positively driven mechanism, and means for placing said arm under control of said mechanism whenever gliding of the fibres in said loop occurs, to cause said arm to be slowly returned to its original position so that a quick return by said weighted pointer and consequent breaking of the strand is avoided and a continuous running of the strand through the apparatus is assured.

5. The method of testing the draft resistance of running cotton roving, which comprises applying a tension slightly less than the required draft resistance to a section considerably longer than the cotton staple, and whenever the draft resistance in that section is less than said tension causing said section to elongate very slowly until said draft resistance in the section again becomes greater'than said tension.

6. The method of testing the draft resistance of running cotton roving, which comprises applying a tension slightly less than the required draft resistance to a section consideraoly longer than the cotton staple, and whenever the draft resistance in that section is less than said tension causing said section to elongate at a fixed rate of speed and under continually decreasing tension until said draft resistance in the section again becomes greater than said tension.

7 The method of determining the necessary twist, without break, of an indeterminate length of continually running, extensible strand material having a relatively short staple which comprises placing a pull, in a degree slightly less than the draft resistance determined by said twist, upon a section of said strand considerably longer than the length of its staple whereby said section will start to elol'igate and tend to. break whenever a portion weaker than said pull enters the section, and causing said elongation to continue, during the period that said weaker portion remains Within the section, ata controlled rate that imparts a pull insuflicient to break said weaker portion.

8. The method of obtaining an indication corresponding to the variable draft resistance of extensible, fibrous strand material, which comprises moving the strand along, progressively under an uncontrolled predetermined tension, transferring control of the strand, whenever its strength is insufficient to prevent gliding of the fibres, to a regulated tension that insures such gliding at a returning to said uncontrolled tension when the draft rolls resistance of the strand becomes sufficient to permit of its running without gliding under said uncontrolled tension.

"9. A machine for testing the draft resistance of extensible fibrous strand material comprising, means 'for progressively advancing the strand, a guide member engaging a section of the running strand that is gripped at each end, a'weighted pendulum connected to said guide member that is held in a prescribed angular position by the normal draft resistance within said section and will fall with increasing velocity when said normal draft resistance is decreased by gliding of the fibres in a weaker portion of the strand causing said-guide member to jerk through the strand, and mechanism made operative by the falling pendulum for modifying the movement of said guide member to prevent a break in the strand.

I 10. A machine for testing the draft resistance in continuously running fibrous extensible strand material comprising a guide member engaging a loop of said strand that is ripped at both ends, a weighted pendulum for causing said member to apply a predetermined pull on said loop, and mechanism permitting said pendulum to move freely ""whenever the loop shortens by reason of draft resistance therein greater than the pull of said member, but to move only at a controlled rate of speed whenever the loop elongates by gliding of the fibres due to a draft resistance therein less than said pull.

11. A machine of the character described comprising, a pair of feeding-in rolls and a pair of delivery rolls, means for driving said to continually advance extensible strand material, amovable arm engaging a section of the running strand between said pairs of rolls having a weight arranged to place a predetermined tension. on said sectiou through said arm whereby the weight will fall with increasing velocity and tend to break the strand whenever the draft resistance within said section is lesst-han the tension determined by said weighted arm, and mechanism for preventing the weight from falling far enough to break the strand comprising a device moving continuously at a fixed rate of speed and means operated by the initial downward movement of the weight for placing said weight under the control of said device.

12. A roving testing machine comprising roller mechanism for feeding-in the roving, roller mechanism for delivering the roving, the delivery mechanism operating to deliver the roving slightly faster than it is fed in, a movable arm engaging a loop of the running roving extending between said feeding-in and delivery mechanisms, means acting on said-arm to place a predetermined tension on said loop, a screw, means for rotating said screw slowly at a fixed rate of speed, and a 

